In a typical cellular wireless network, multiple base station subsystems are coupled to a mobile switching center (MSC). Each base station subsystem (BSS) includes multiple base transceiver stations that communicate with wireless mobile units using one or more air interfaces. Each BSS also includes a base station controller (BSC) that manages the base transceiver stations and that communicates with the MSC. Each BSC is connected to the MSC using a suitable communication link. The link between each BSC and the MSC is also referred to here as the “backhaul” link.
One common BSS configuration is a “macrocell” configuration in which relatively few high-powered, high-capacity base transceiver stations provide wireless coverage within a relatively large geographic area (also referred to as a “macrocell”). However, conventional macrocell BSS equipment is typically large and requires a central site in which to deploy the BSC equipment. Thus, conventional macrocell BSS equipment may not be suitable in some applications.
Other BSS configurations make use of relatively low-powered, low-capacity base transceiver stations that provide wireless coverage within a relatively small geographic area. Examples of such BSS configurations include “microcell” and “picocell” configurations. The use of such alternative BSS configurations provides additional flexibility in configuring a cellular wireless network.
However, issues can arise with using such alternative BSS configurations with MSC equipment that was designed for use with conventional macrocell BSS equipment. For example, it may be difficult from a network planning and management standpoint to use conventional MSC equipment with a large number of BSSs that are implemented using different types of BSS equipment since the MSC may not be able to be configured to work with multiple different types of BSS equipment at the same time.
Moreover, in some applications, the backhaul link is implemented using a relatively expensive communication link such as a satellite link. In such applications, it is desirable to reduce the amount of data that must be communicated over this backhaul link. One way to do this is to use local switching within each BSS, where calls between two mobile units that are served by the same BSS are cross-connected within the BSS. In this way, the call data for such locally switched calls need not be communicated over the backhaul link to the MSC for switching by the MSC.
In US Patent Publication 2008-0310404 (U.S. patent application Ser. No. 11/914,633, filed on Aug. 8, 2008), a local switching scheme is described in which local media gateways are co-located within each BSS. In this scheme, in order for a call between two mobiles units that are both served by the same BSS to be locally switched, the MSC is modified to include functionality that selects the appropriate local media gateway to locally switch the call. In other words, with this local switching scheme, the MSC is modified to support locally switching.